Numerical Responses of Martens to a Food Shortage in Northcentral Ontario

Abstract

Numerical responses of martens (Martes americana) to a synchronous decline of most prey species were studied from 1980 to 1985. Main prey species included snowshoe hare (Lepus americanus), red squirrels (Tamiasciurus hudsonicus), southern red-backed voles (Clethrionomys gapperi), deer mice (Peromyscus maniculatus), and ruffed grouse (Bonasa umbellus). Populations of these prey species were high in 198081 and substantially reduced from 1982 to 1985, except ruffed grouse, which were abundant in 1984-85. Responses of martens included reduced population density, enlarged home ranges, lower ovulation rates in females aged 1 and 2 years, reduced production of young, dispersal of formerly resident adults during the 2nd year of scarce food, and cannibalism. Dispersal of residents resulted in an unexpectedly high trapping success in 1983, suggesting that fur returns do not reflect changing population levels for marten. Male body weights did not differ among years but females weighed more in early winter of scarce food years compared to the same period when food was abundant (P < 0.01). Less mesenteric and renal fat was found on all martens during the 1st winter of scarce food (P < 0.001). We believe that a reservoir strategy for marten management can be an effective tool, but when food is low managers must account for larger home ranges and possible dispersal of residents by reducing harvest quotas. J. WILDL. MANAGE. 51(4):824-835 Factors that naturally regulate populations of animals are of considerable interest to wildlife managers. Reduced conception rates and early mortality of neonates resulting from food scarcity have been implicated as common factors affecting the population dynamics of many small carnivores (Erlinge 1974, 1983; Brand et al. 1976; von Schantz 1984). The marten is an important fur-bearing species in Ontario, but few data are available on mechanisms that control their populations. Weckwerth and Hawley (1962) suggested that this species is food limited, mediated through juvenile mortality and poor conditions of adult females. In Scotland Lockie (1964) presented evidence that a population of the European pine marten (Martes martes) fluctuated independently of its principal prey, the shorttailed vole (Microtus agrestis). However, he did not sample the populations of other potential foods. During a 4-year investigation into the effects of timber harvesting on martens, we observed a local decline in prey populations. Our objecPresent address: Canadian Forestry Service, Newfoundland Forestry Centre, Box 6028, St. John's, Newfoundland AIC 5X8, Canada. This content downloaded from 207.46.13.83 on Fri, 13 May 2016 07:06:29 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 51(4):1987 FOOD SHORTAGE IN MARTENS * Thompson and Colgan 825 tive is to describe numerical responses of martens to reduced food, including changes in production, population, home range size, dispersal, age structure, weights, and amounts of body fat. We conclude with a discussion of management of marten based on food limitations. The authors gratefully acknowledge the logistic support of P. Martindale and the Ont. Minist. Nat. Resour. at Manitouwadge, and R. Collings and the Am. Can Co. of Can. at Camp 15. This project was supported in part by the Ont. Minist. Nat. Resour. and the Ont. Board Industrial Leadership and Dev. We also wish to thank numerous students and contractors for their efforts, in particular I. Davidson and S. O'Donnell. F. Brazeau provided able technical assistance for 3 years. D. Welsh, D. Euler, and R. A. Lancia provided critical comments on earlier drafts.